EDSAC Full Form: Electronic Delay Storage Automatic Calculator

The full form of EDSAC is Electronic Delay Storage Automatic Calculator. EDSAC was an early British stored-program computer built by Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory. It ran its first program on 6 May 1949 and became the first computer to offer a regular computing service to other scientists. In Hindi, EDSAC ka full form is also “Electronic Delay Storage Automatic Calculator”; the name is not translated.

What each word in EDSAC means

• Electronic: it computed with vacuum tubes (valves), about 3,000 of them, instead of mechanical relays.
• Delay Storage: its main memory was a set of mercury delay lines. Data travelled as sound pulses through tubes of mercury and was re-circulated, so a bit was “stored” by keeping it moving.
• Automatic: once a program was loaded from paper tape, the machine ran without a human setting switches for each step.
• Calculator: the word used at the time for a general-purpose computing machine.

EDSAC key facts

Why EDSAC matters in computer history

EDSAC was designed after Wilkes read John von Neumann’s 1945 report on the EDVAC, which described storing programs in the same memory as data. The Manchester “Baby” had already run a stored program in June 1948, but it was an experimental machine. EDSAC was the first stored-program computer built to do useful work every day for other people.

Several ideas that programmers still use began on EDSAC:

• Subroutines and libraries. David Wheeler invented a way to call a reusable block of code and return from it (the “Wheeler jump”), and the team built one of the first subroutine libraries.
• An assembler-like loader. Wheeler’s “initial orders” let programmers write instructions with letters and decimal numbers instead of raw binary.
• The first programming textbook. Wilkes, Wheeler and Gill published The Preparation of Programs for an Electronic Digital Computer in 1951.
• Early computer game. In 1952 A. S. Douglas wrote OXO, a noughts-and-crosses game on EDSAC, often cited as one of the first video games.

EDSAC also did serious science. It was used in calculations for Nobel Prize-winning work, including John Kendrew’s study of the structure of myoglobin and Martin Ryle’s radio astronomy.

EDSAC vs EDVAC vs ENIAC

EDSAC’s legacy

The catering company J. Lyons & Co. helped fund EDSAC and then built LEO I (Lyons Electronic Office) on its design, which in 1951 ran the world’s first routine business computer job. A working replica of EDSAC has been rebuilt by volunteers at The National Museum of Computing at Bletchley Park in England.

Frequently asked questions

What is the full form of EDSAC?

EDSAC stands for Electronic Delay Storage Automatic Calculator.

Who invented EDSAC?

EDSAC was designed and built by Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory.

When was EDSAC built?

EDSAC ran its first program on 6 May 1949 and remained in service until 1958.

What memory did EDSAC use?

EDSAC used mercury delay lines, which stored bits as sound pulses travelling through tubes of mercury. It began with 512 words of memory, later expanded to 1,024.

Was EDSAC the first stored-program computer?

Not quite. The Manchester Baby ran a stored program first, in June 1948. EDSAC was the first practical stored-program computer to run a regular service for users.

References

• M. V. Wilkes, D. J. Wheeler and S. Gill, The Preparation of Programs for an Electronic Digital Computer (1951).
• University of Cambridge Computer Laboratory, EDSAC history pages; The National Museum of Computing, EDSAC Replica Project.